Circuit protectors and methods of assembling the same

ABSTRACT

A circuit protector consisting of a pair of assemblies, each of which has both a spark-gap protector for excessive voltage and a heat-coil protector for excessive current buildup, is provided with two springs, one of which is associated with each assembly. Each spring holds various elements of one of the assemblies in abutment and propels a grounding pin released by the associated heat-coil protector when excessive current buildup is encountered in an accompanying circuit. Only one spring is needed with each assembly because a contact pin associated with each assembly floats within the circuit protector and is, therefore, subject to the force of the spring allowing the spring to urge the various elements of the assembly into abutment. By modifying a housing within which the assemblies are mounted, the assemblies are moved into close proximity to thereby minimize the width of the circuit protector.

United States Patent [72] Inventors 2,619,518 11/1952 Kelsay..... 337/32X 2,546,824 3/1951 Koliss........................... '337/29 Primary Examiner-Bernard A. Gilheany Assistant Examiner-Dewitt M. Morgan James B. Geyer Baltimore;

William D. OBrien, J r., Reisterstown; Stephen A. Reisinger, Carney, Md. [211 App]. No. 858,984 Filed sept- 18, 1969 Attorneys W. M. Kain, R. P. Miller and Don P. Bush [45] Patented Apr. 6, 1971 [73] Assignee Western Electric Company, Incorporated New York ABSTRACT: A circuit protector consisting of a pair of assemblies, each of which has both a spark-gap protector for excessive voltage and a heat-coil protector for excessive current [54] CIRCUIT PROTECTORS AND METHODS OF buildup, is provided with two springs, one of which is as- ASSEMBLING THE SAME sociated with each assembly. Each spring holds various elements of one of the assemblies in abutment and propels a 13 Claims, 16 Drawing Figs.

grounding pin released by the associated heat-coil protector when excessive current buildup is encountered in an accompanying circuit. Only one spring is needed with each assembly because a contact pin associated with each assembly floats within the circuit protector and is, therefore, subject to the force of the spring allowing the spring to urge the various elements of the assembly into abutment. By modifying a housing within which the assemblies are mounted, the assemblies are [5 6] References Cited UNITED STATES PATENTS 3,255,330 6/1966 MacKenzie et a1.

moved into close proximity to thereby minimize the width of the circuit protector.

Patented April 6, 1971 5 Sheets-Sheet 2 RJOR ART I- I a T R A R l R P Patented April 6, 1971 5 Sheets-Sheet 5 Patented April 6, 1971 Y 3,573,695

5 Sheets-Sheet 4 Patented A ril 6, 1911 5 Shoots-Sheet 5 CIRCUIT PROTECTORS AND METHODS OF ASSEMBLING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electrical protective devices and more particularly to protector devices which protect against both excessive voltage and excessive current and methods of assembling these devices.

2. Description of the Prior Art In modern telephone engineering, it is usual practice to provide combined protectors at central offices for each incoming telephone line. These protectors combine protection against excessive voltages resulting, for example, from lightning, with protection against so-called sneak currents which are not strong enough to do any damage if they flow briefly but which might generate enough heat to char insulation and do other damage if allowed to persist. The sneak currents are produced by voltages of relatively low magnitudes as compared to the excessive voltages first mentioned and usually result from accidental interference between telephone lies and adjacent power lines.

Protection against excessive voltage is usually provided by so-called open-gap protectors which generally include a pair of spaced carbon electrodes. One of the electrodes is usually connected to ground and the other of the electrodes is usually connected to the incoming telephone line. Should a high voltage be impressed on the line, it will bridge the space or gap between the electrodes and flow to ground, thus bypassing sensitive equipment associated with the line.

The second type of protection is commonly provided by a device usually referred to as a heat coil. The heat coil consists essentially of a coil of fine resistance wire wound on a metal sleeve inside of which a contact pin is held in a predetermined position by solder. Should excessive currents be impressed on the line and persist, sufficient heat will be generated by the coil of wire to melt the solder and release the pin. Aline spring is usually provided which will then push the released pin forward into contact with a carbon block which, in turn, engages a ground plate to ground the line and protect the sensitive line equipment.

The U.S. Pat. No. 2,546,824, which was issued to P. I. Koliss on Mar. 27, I951, disclosed a protector assembly currently in use. This design utilizes a pair of springs, one of which retains the elements of the assembly in abutting relation and the other of which urges a contact pin into engagement with a grounded element when the pin is released by a current buildup in the heat coil that melts a solder joint retaining the pin in retracted position within a sleeve.

Since each telephone has a ring circuit and a talk circuit, each telephone line requires two protector assemblies. Another prior art design discloses two protector assemblies enclosed in a single insulating housing to save space, protect the assemblies from dust and facilitate installation. This design utilizes one spring to retain the elements of the assembly in abutting relation and an additional spring to urge a contact pin into engagement with a grounded element.

Both of the aforementioned prior-art protector assemblies require two springs for effective assembly and operation. Since hundreds of thousands of these protectors are produced annually, deletion of one spring in each protector assembly and transference of its function to the other spring would result in substantial cost reductions.

SUMMARY OF THE INVENTION It is an object of this invention to provide new and improve electrical circuit protectors and methods of assembling the same.

A further object of this invention is to reduce the size and cost of electrical circuit protectors by reducing the number of separate elements in each protector assembly.

A further object of this invention is to provide a new and improved circuit protector having floating contact pin assemblies which transmit spring forces so as to reduce the number of springs necessary in each protector.

Still another object of this invention is to provide a new and improved circuit protector having a protector housing and base which snap fasten together instead of fastening together with a screw in order to reduce the time of assembly and the size of the protector.

A further object of this invention is to reduce the overall size and cost of electrical circuit protectors by precisely electrically isolating the various parts thereof.

Still another object of this invention is to provide new and improved circuit protectors which assure fast and accurate assemblies by utilizing previously assembled subassemblies.

An additional object of this invention is to provide a new and improved circuit protector in which there is an external indication when internal components are incorrectly oriented.

A circuit protector assembly illustrating certain principles of the invention is proved with a spark-gap protector to safeguard against excessive voltages and a heat-coil protector to safeguard against excessive current. The spark-gap and heat-coil protectors are held in abutting, aligned relation by a single spring which also serves to urge a grounding pin which is released to slide in a sleeve when the heat coil receives excessive current and melts a solder joint that normally holds the pin retracted within the sleeve. When released from the sleeve, the grounding pin diverts current from equipment associated with the circuit and carries it to ground. A contact pin is associated with the protector assembly and floats relative thereto subject to the force of the single spring, thereby allowing the spring to urge the spark-gap and heat-coil protectors into aligned relation.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and features of the present invention will be more readily understood from the following detailed description of specific embodiments thereof when read in conjunction with the appended drawings, in which:

FIG. I is a perspective view of a plurality of protectors mounted in a connector;

FIG. 2 is an end view of a prior art protector;

FIG. 3 is a vertical front view of the prior art protector of FIG. 2 with part of a housing and certain of the elements broken away for clarity;

FIG. 4 is an enlarged exploded perspective view of a circuit protector embodying certain features of the present invention;

FIG. 5 is an end view of the circuit protector of FIG. 4;

FIG. 6 is a vertical side view of the circuit protector of FIG. 4 with part of a housing and certain of the elements broken away for clarity;

FIG. 7 is a vertical front view of the protector embodying certain features of the present invention with part of a housing and certain of the elements broken away;

FIG. 8 is a portion of the circuit protector of FIG. 6 showing a pin of a heat coil in an operated position;

FIG. 9 is an inverted vertical side view of the housing of FIG. 4 with part of the housing broken away for clarity showing a grounding pin bracket assembly in an intermediate position;

FIG. 10 is an inverted front perspective view of the housing of FIG. 4 with part of the housing broken away for clarity showing the grounding pin assembly in the intermediate position shown in FIG. 9;

FIG. 11 is an inverted perspective view of the housing of FIG. 4 with part of the housing broken away for clarity showing how a pair of spark-gap'protectors are inserted into the housing and rest on the grounding pin assembly;

FIG. 12 is an end view of the housing of FIG. 4 taken along line 12-12 thereof showing various rib retaining means used to secure various elements in the housing;

FIG. 13 is an inverted perspective view of the protector of FIG. 4 with part of the housing broken away for clarity and certain of the elements deleted showing how the subassembly of FIG. 13 is inserted into the housing after the grounding pin bracket and spark-gap protectors are in place;

FIG. 14 is an inverted exploded perspective view of the circuit protector of FIG. 4 showing a base being inserted into the end of the housing after the grounding pin bracket, spark-gap protectors and subassemblies have been inserted;

FIG. 15 is an inverted vertical side view of the circuit protector of FIG. 4 with part of the housing broken away showing the base partially inserted into the housing during the assembly operation, and

FIG. 16 is an inverted vertical view similar to FIG. 15 showing the base fully inserted into the housing,

DETAILED DESCRIPTION Referring now to FIG. 1, there is shown a connector, designated generally by the numeral 20, having a plurality of sockets 21-21 therein for receiving a plurality of pins 22-22, 23-23, and 24-24 projecting from an array of circuit protectors, designated generally by the numerals 26-26. Upon considering FIG. 1, it becomes readily apparent that each connector has many circuit protectors 26-26 mounted thereon. It follows that even a slight reduction in size of each of the circuit protectors 26-26 will enable each connector 20 to accommodate many more protectors per unit surface area. Furthermore, since many circuit protectors 26-26 are used, a reduction in the number of elements composing each circuit protector will result in substantial monetary savings.

FIGS. 2 and 3 are illustrative of the prior art in which a pair of substantially identical protector assemblies, designated generally by the numerals 27 and 28, are retained in a plastic housing 29 by a screw-fastened base 30 to form a circuit protector, designated generally by the numeral 31. Portions of some of the elements of each of the protector assemblies 27 and 28 have been broken away to expose certain features of the circuit protector 31, however, it is to be understood that protector assembly 27 is substantially identical to circuit protector assembly 28. Each of the protector assemblies 27 and 28 have a pair of ground springs 32-32 which hold the elements of a pair of spark-gap protectors, designated generally by the numerals 33-33, in aligned abutment and provide electrical paths to ground. A pair of line springs 34-34 urge a pair of grounding pins 35-35 into engagement with a pair of carbon protector inserts, designated generally by the numerals 36-36, when excessive current buildup in a pair of heat-coil protectors, designated generally by the numerals 37-37, melts solder connections (not shown) between the pins 35-35 and a pair of retaining sleeves 38-38. It should be noted that a pair of contact pins 39-39 of the prior art protector 31 are secured rigidly to the base 30 thereby preventing the springs 34-34 from biasing the elements of the spark-gap protectors 33-33 into abutment. The ground springs 32-32 are, therefore, needed to bias the elements of the spark-gap protectors 33-33 into abutment. The prior art protector 31 differs generally from the present invention in that (1) the present invention uses only one spring in each assembly whereas the prior art uses two; (2) the housing of the present invention has a snapfastened base; whereas the prior art housing has a screwfastened base; and (3) the centerlines of the respective pairs of protector assemblies have been moved closer together. All of these differences contribute to the smaller size of the protector of the present invention.

Referring now to FIGS. 4-8, inclusive, of the drawings, there is illustrated a preferred embodiment of the circuit protector 26 embodying certain principles of the present invention and intended to replace the aforementioned circuit protector 31. A plastic housing, designated generally by the numeral 41, is shown with a base 42 snap fastened thereto by two pairs of tungs 43-43 on the base engaging two pairs of slots 44-44 in the housing, thus retaining the entire assembly without using a screw. A finger grip 45 is provided adjacent the one end, designated generally by the numeral 46, of the housing 41 and a compartmentalizing rib 47 (FIG. 6) extends from one inner wall partially across the housing.

Referring now to FIGS. 4 and 7, a pair of structurally identical protector assemblies, designated generally by the numerals 48 and 49, are enclosed in the housing 41 and separated partially by the compartmentalizing rib 47 (FIG. 6) to form protector assemblies for a ring circuit (not shown) and a talk circuit (not shown), respectively, of an associated telephone line (not shown).

The protector assemblies 48 and 49 are connected to the common grounding pin 24 through a grounding bracket, designated generally by the numeral 51, which has a pair of ground plates 52-52 which both assemblies abut. The ground plates 52-52 are connected to the grounding pin 24 through a strap 53 which is formed integrally with and extends normal to the ground plates. The strap 53 has a tab 54 oriented at right angles thereto in which the pin 24 is staked. The grounding pin 24 serves to ground excessive voltages and excessive current in either of the aforementioned telephone circuits connected thereto. To facilitate ease of assembly, the grounding pin 24 is free to slide in a bore 56 of base 42 against the bias of the pair of springs 34-34 as will be explained further later.

The elements of each of the protector assemblies 48 and 49 are shown in an exploded perspective view in FIG. 4 and in section in FIGS. 6, 7 and 8. In each of the assemblies 48 and 49, the spaced-gap or spark-gap protectors 33-33 directly engage the ground plates 52-52. The spark-gap protectors 33-33 consist of the cylindrical carbon protector inserts 36-36 seated permanently in bores 57-57 of apertured ceramic sleeves 59-59. The carbon protector inserts 36-36 project from one end of the ceramic sleeves 59-59 and are each recessed approximately 3 mils from the opposite ends of the sleeves. Carbon protector blocks 60-60 abut the opposite ends of the sleeves 59-59 and are, thereby, spaced approximately 3 mils from the protector inserts 36-36 creating spaced gaps 61-61. When a surge of excessive voltage is generated in the telephone line by a lightning strike, or the like, the resulting potential will enter the circuit protector 26 through the ring circuit (not shown) protected by protector assembly 48, the talk circuit (not shown) protected by protector assembly 49, or both of the circuits. Assuming that the potential enters through the ring circuit, it will bridge the associated gap 61 between the carbon insert 36 and the block 60 of the protector assembly 38 and then be conducted to ground by the grounding pin 24.

The set of carbon protector blocks 60-60 are seated against apertured legs 63-63 on U-shaped brackets, designated generally by the numerals 65-65. The blocks 60-60 have axial bores 66-66 therethrough which are aligned with oblong apertures 67-67 in the legs 63-63. The bores 66-66 and the apertures 67-67 accommodate contact pins 35-35 of the heat-coil protectors 37-37, the operation of which will be explained later.

Contact pins 22-22, which are connected to the telephone line, are secured rigidly to the brackets 65-65 on apertured legs 73-73 opposite the legs 63-63. The pins 22-22 are received slidably through bores 74-74 in the base 42 and the base is relieved in area 76-76 around the bores so that the legs 73-73 holding the pins have room to reciprocate freely with respect to the base.

The protector assemblies 48 and 49 have one of the line springs 34-34 positioned within each of the associated U- shaped brackets 65-65. Ends 77-77 of each of the line springs 34-34 abut associated line plates 79-79 which are secured rigidly to pins 23-23. The pins 23-23 pass through bores 81-81 (FIG. 4) in the base 42 and are prevented from sliding therein by shoulders 82-82 on the pins which engages the base 42 adjacent to the bores 81-81. The pins 23-23, in conjunction with pins 22-22, connect the protector assemblies 48 and 49 to the associated telephone line (not shown) through the connector board 20 (FIG. 1).

The other ends of the line springs 34-34 engage the aforementioned heat-coil protectors 37-37. The heat-coil protectors 37-37 include insulating shells, designated generally by the numerals 83-83, (FIGS. 6 and 8), having projecting portions 84-84 seated within the coils of the springs 34-34. The

aforementioned pins 35-35 are retained rigidly by the shells 83-83 and project a sufficient distance therefrom to accommodate the sleeves 38-38 therearound and to make electrical contact with the carbon inserts 36-36 when operated. The sleeves 38-38 are soldered to the pins 35-35 at predetermined locations spaced from both the shells 83-83 and the end of the pins, thereby allowing the pins to slide within the sleeves when the solder is melted (FIG. 8). Flanges 87-87 project radially from one end of the sleeves 38-38 providing flat surfaces for abutment with the legs 63-63. Additional flanges 88-88 at the other end of the sleeves 38-38 are spaced far enough from the shells 83-83 so that when the pins 35-35 slide within the sleeves 38-38, the pins will engage the carbon inserts 36-36 before the shells 83-83 can engage the flanges 88-88, thus insuring electrical contact between the pins and the carbon inserts 36-36.

Single small diameter wires 89-89 are coiled about each of the sleeves 38-38 between flanges 87-87 and 88-88 to form the heat coil windings 90-90 (FIG. 4). The wires 89-89 have one end electrically connected to the sleeves 38-38 and the other ends electrically connected to conducting caps 91-91 which surround and are secured to enlarged portions 92-92 of the insulating shells 83-83. The conducting caps 91-91 abut the springs 34-34, thereby creating an electrical connection between the heat-coil protectors 37-37 and the springs.

As seen in FIGS. 6 and 7, the line springs 34-34 urge the other elements of the protector assemblies 48 and 49 into abutting relation with the ground plates 52-52 which are, in turn, urged into abutting relation with the end 46 of the housing 41. The ground plates 52-52 and the brackets 65-65 are rigidly attached only to the grounding pin 24 and the contact pins 22-22, respectively. Since the pins 24 and 22-22 are slidable in their respective bores 56 and 74-74, the bracket 51 and the brackets 65-65 are, therefore, slidable within the housing 40 against the bias of the springs 34-34. When the base 42 is pressed into snap fit with the housing 40, variations in tolerance among the elements of the assemblies 48 and 49 are accommodated by the deflection of the springs 34-34 because the brackets 65-65 are allowed to float against the bias of the springs. After the circuit protector assemblies 48 and 49 are completely assembled, the grounding pin 24 and the contact pins 22-22 are restrained from moving toward the end 46 of the housing 40 because the pins are in rigid abutment relative to the end 46 of the housing. The pins 24 and 22-22, therefore, will not move as the protector assembly 26 is plugged into the connector panel 20 (FIG. 1). Since the pins 22-22 float relative to the base 42, the springs 34-34 of the present invention are able to assume the function of the ground springs 32-32 of the prior art protector 31 (FIG. 3) by urging the sleeves 59-59 and the blocks 60-60 of the sparkgap protectors 33-33 into abutment with one another and by urging the protectors into direct abutment with the ground plates 52-52.

ASSEMBLY OF THE PRESENT INVENTION Referring to FIGS. 9 through 16, the various steps involved in assembling the circuit protector embodied in the present invention are seen in sequence. Since the housing 41 of the protector 26 is narrower than the housing 29 of the prior art protector 31, it is necessary to use a different method of assembly. FIGS. 9 and show the grounding bracket 51 supported in an intermediate position within the housing 41 on a shoulder 95 projecting from the rib 47. The grounding plates 52-52 intersect to form the groove 96 which rests upon the shoulder 95 when the grounding bracket 51 is in the intermediate position shown in F105. 9 and 10. The stem portion 53 has two projections 98 and 99 thereon which sit within a slot 101 formed between two projecting portions 102 and 103 on the housing 24 with which the spark-gap protectors would interfere if the grounding pin assembly were in a purely vertical orientation.

As seen in FIG. 11, the spark-gap protectors 33-33 are inserted into the housing 41 and come to rest on the grounding plates 52-52 of the grounding bracket 51. In order to facilitate insertion of the spark-gap protectors 33-33 a vacuum system (not shown) is used to lower the spark-gap protectors in place. After the spark-gap protectors 33-33 are seated upon the grounding bracket 51, the bracket is lowered into the housing 41 until the grounding plates 52-52 seat against the end 46 of the housing and within the confines of a shoulder 104 which projects from the end 46 of the housing a distance greater than the thickness of the grounding plates. If either or both of the spark-gap protectors 33-33 are oriented in the wrong direction, so that a projecting end 107 of one of the inserts 36-36 does not abut one of the grounding plates 52-52, or if one or both of the protector blocks 60-60 are inserted into the housing 41 ahead of the respective sleeves 59-59 containing the inserts 36-36, the errant spark-gap protector will rest on a platform 106 adjacent the shoulder 104 and the projecting portion 107 thereof will not be accommodated by a recessed portion 108 formed and defined by the shoulder 106. When incorrectly oriented, the spark-gap protectors 33-33 project a further distance from the end 46 of the housing 41 than the spark-gap protectors would project if oriented in the right direction, thereby making the pins 22-22 overextend from the end of the housing. Indication is thereby given that at least one of the spark-gap protectors 33-33 has been assembled in the wrong order or has been otherwise assembled incorrectly.

A pair of L-shaped retaining ribs 111 and 112 electrically isolate and securely retain the strap 53 therebetween when the grounding bracket 51 is inserted completely in the housing 41 so that the grounding plates 52-52 seat against the end 46 of the housing and within the recessed portion 108 of the housing. The L-shaped ribs 111 and 112 accommodate slidably the projections 98 and 99 on the stem 53 and lock the bracket 51 in place by preventing the bracket from pivoting.

Referring now to FIG. 13, one of the bracket assemblies 65-65 associated with the contact pins 22-22 is shown as a separate unit containing the spring 34 and the heat-protector assembly 37. Prior to inserting the spring 34 and the heat protector assembly 37, a slot 113 is cut in the bracket 65 before the pin 22 is staked to the flange 73. The slot 113 allows you to bend the bracket 65 to form the flange 73 without distorting a hole 114 (FIGS. 15 and 16) within which the pin 22 is staked. In order to support the spring 34, a reduced diameter portion 116 of the pin 22 projects through the hole 114 and beyond the surface of the flange 73 to engage an inner surface 117 of the spring 34 (see FIGS. 15 and 16). Since the projecting portion 84 of the insulating shell 83 is retained within one end of the spring 34 and the pin 35 projects through the oblong slot 67, both the spring and heat coil 37 are securely held between the leg 63 andflange 73 of the bracket 65 by the compressive force of the spring.

As seen in FIG. 13, the bracket assemblies 65-65 are slid into the housing 41 after the grounding bracket 51 and sparkgap protectors 33-33 are inserted into the housing. In order to restrain and electrically isolate the brackets 65-65 within the housing 41, L-shaped ribs 119 and 121 are positioned adjacent the separating rib 47 and form retention slots 123 and 124 with additional ribs 126 and 127 which are respectively situated in opposed relation to the ribs 119 and 121. Another pair of ribs 129 and 131 cooperate with-the ribs 111 and 112 to form slots 132 and 133 to accommodate the legs 63-63 of the bracket assemblies 65-65 and to, thereby, further restrain the bracket assemblies from rotational movement during insertion of the bracket assembly into the housing.

Referring now to FIGS. 14 through 16, the base 42 which has the pins 23-23 secured thereto in electrical engagement with the shoes 79-79 is shown being inserted into the housing 41. When the base 42 is pressed from its position in FIG. 15 into the housing 41 as shown in FIG. 16, the shoes 79-79 engage the springs 34-34 and compress the springs moving the springs against the pair of ribs 126 and 127 which cam the springs away from electrical connection with strap portions 135-135 of the bracket assemblies 65-65 as the shoes move the springs away from the legs 73-73. The springs 34-34 and the heat-coil protectors 37-37 are thereby moved out of direct electrical contact with the pins 22-22 establishing normal electrical paths which follow, respectively, through the pins 22-22, the legs 73-73 the straps 135-135, the legs 63-63, the heat coil 37-37, the springs 34-34, the shoes 79-79 and the pins 23-23. When the end cap assembly 32 is fully inserted, flanges 134 seat against a rim 136 on the housing 41 and the openings 44- 44 snap over the detents 43-43 to hold the entire circuit protector assembly 16 securely together.

OPERATION OF THE PRESENT INVENTION The protector assemblies 48 and 49 are inserted into the connector 20 with the contact pins 22-22 plugged into the outside telephone line (not shown). The pins 23-23 are plugged into an associated circuit (not shown) and the grounding pin 24 is plugged into ground. Ordinarily, the protector assembly 48 is connected to the ring circuit of the telephone line and the protector assembly 49 is connected to the talk circuit of the telephone line, however, the operation of both protector assemblies is identical. For purposes of illustration, only the operation of protector assembly 48 will be discussed. Normally, the telephone line current follows a path leading from the pin 23, into the plate 79, through the spring 34, the cap 91, the heat-coil wire 90, the bracket 65, and out of the pin 22. When there is a surge of high voltage, as when lightning hits the telephone line, the electron flow enters the pin 22, travels through the bracket 65, bridges the gap between protector block 60 and the insert 36, flows to grounding bracket 51 and out of the grounding pin 24, thus bypassing the normal line circuit and averting probable damage. Unusually high potential will create an arc across the 3 mils gap 61 between the protector block 60 and insert 36. As long as the high potential is applied, the arc will be sustained and will offer a low resistance path to the electron flow thus diverting excessive potentials. After the surge is dissipated, the protector assembly 48 continues to function normally.

When there is a relatively low current buildup or an initial excessive current, as when a power line interferes with the telephone line, the resistance wire 89 of the heat coil winding 90 heats up and melts the solder joint (not shown) between the pin 35 and the sleeve 38. The spring 34 then urges the pin 35 through the bore 66 into engagement with the insert 36 to ground the telephone line on the bracket 51 so that the current flows to ground through the pin 24 and bypasses the telephone line to which the pin 23 is connected. Once the solder has been melted and the pin 35 has been moved, the heat-coil protector 37 must be replaced.

By the aforementioned operation, the present invention protects telephone line circuits against both excessive voltage and excessive currents.

We claim: 1. An electrical protector assembly for protecting a circuit against excessive voltage surges and excessive current increases, comprising:

retaining means for supporting the assembly; grounding means seated in said retaining means, said grounding means grounding excessive voltage surges and excessive current increases which appear in said circuit;

at least one spark-gap means urged directly into abutting relation with said grounding means for conducting excessive voltage surges to said grounding means;

at least one first electrical contact means for establishing contact between the circuit and the assembly, said first electrical contact means abutting said spark-gap means; at least one second electrical contact means secured to said retaining means and spaced from said first electrical contact means, said second electrical contact means and said first electrical contact means adapted to conduct normal circuit current with the application of normal circuit voltage;

at least one current responsive means having a projectable element thereon for establishing an electric circuit with said grounding means when the current increases beyond a predetermined level, said current responsive means being aligned with said spark-gap means and urged into abutting relation with said first electrical contact means; and

at least one spring means abutting said current responsive means and said second electrical contact means to (l) establish a conducting path for normal circuit current at normal applied circuit voltage, to (2) urge said spark-gap means into direct engagement with said grounding means and to (3) urge said projectable element into electrical connection with said grounding means when the current increases beyond a predetermined level.

2. The assembly of claim 1 wherein said first electrical contact means is slidable relative to said retaining means against the force of said spring means.

3. The assembly of claim 1 wherein said grounding means includes:

a grounding pin for establishing direct engagement with the circuit to be protected;

a strap member extending in said assembly and being made of a substantially flat strip of conducting material for conducting excessive voltage surges and excessive current increases from said spark-gap means and said currentresponsive means to said pin member; and

a pair of tabs projecting laterally from said strap member, one of said tabs being abutted by said spark-gap means and being aligned with and spaced from said projectable element of said current-responsive means and the other of said tabs supporting said grounding pin thereon.

4. The assembly of claim 1 wherein said first electrical contact means includes:

a contact pin for establishing direct engagement with the circuit to be protected;

a strap member extending in said assembly for establishing a conducting path with said contact pin; and

a pair of tabs projecting laterally from said strap member, one of said tabs having a closed oblong recess therein for retaining said projecting element of said current responsive means and the other of said tabs having said contact pin secured thereto with a portion of said contact pin projecting through said other of said tabs, said portion temporarily engaging and retaining said spring means when said spring means is assembled with said current-responsive means between said tabs to facilitate the subsequent assembly of the first electrical contact means and the spring means with said retaining means.

5. The assembly of claim 1 wherein the retaining means comprises:

a housing having at least one open end;

a base means securable to said open end, said base means having said second contact means rigidly attached thereto;

rib means extending longitudinally in said housing and projecting partially across the width of said housing, said rib means having support means thereon for supporting said grounding means in an intermediate position;

slot means disposed directly opposite said rib means for retaining said grounding means in a final position, said slot means electrically isolating said grounding means from a portion of said spark-gap means, from said current responsive means and from said spring means;

first and second additional slot means disposed adjacent to said rib means on either side thereof for retaining said first electrical contact means and for camming said spring means during the assembly of said electrical protector assembly; and

means on said housing for securing said base on said housing after said base is slid into position on said housing. 6. The assembly of claim 5 further comprising:

said housing formed with at least one closed end; and

a shoulder projecting from said closed end of said housing adjacent to said grounding means when said grounding means is seated in said retaining means, said shoulder defining a recess encompassing a portion of said grounding means and having a height greater than the thickness of said portion, said recess also encompassing a portion of said spark-gap means when said spark-gap means is correctly oriented and not encompassing a portion of said spark-gap means when said spark gap is incorrectly oriented, wherein said spark-gap means projects further from the closed end of the housing and causes said first electrical contact means to project excessively beyond said open end of said housing when said spark-gap means is incorrectly oriented.

7. A method of assembling the electrical protector of claim 1 comprising the steps of:

positioning said grounding means in said retaining means to support said grounding means in said retaining means in an intermediate position;

positioning said spark-gap means in said retaining means to locate said spark-gap means on said grounding means;

moving said grounding means with said spark-gap means located thereon to a final position within said retaining means;

moving said first electrical contact means with said currentresponsive means and said spring means secured thereto to position said first electrical contact means in abutting relation with said spark-gap means;

electrically connecting sad second electrical contact means with said spring mean; and

camming said spring means out of direct abutment with said first electricalcontact means simultaneously with electrically connecting said second electrical contact means with said spring means.

8. The method of claim 7 wherein said grounding means is tilted relative to said retaining means when in said intermediate position and is longitudinally aligned with said retaining mans when being moved to said final position and when in said final position.

9. An electrical protector assembly for protecting a plurality of normally separate electrical circuits from excessive voltage surges and excessive current increases in the circuits compris- In I retaining means for supporting the assembly;

grounding means seated in said retaining means for ground ing excessive voltage surges and excessive current increases which may appear in any of said circuits;

a plurality of juxtaposed spark-gap means urged directly into abutting relation with said grounding means for conducting excessive voltage surges in any of said circuits to said grounding means;

a plurality of juxtaposed first electrical contact means for establishing contact between the circuits and the assembly, each of said first electrical contact means abutting one of said spark-gap means;

a plurality of juxtaposed second electrical contact means secured to said retaining means and spaced from said plurality of said first electrical contact means, said plurality of said second electrical contact means and said plurality of said first electrical contact means adapted to conduct normal circuit current with the application of normal circuit voltage in said plurality of circuits;

a plurality of juxtaposed current responsive means each having projectable elements thereon for establishing and electrical circuit with said grounding means when the current in an associated circuit increases beyond a predetermined level, said plurality of current-responsive means being aligned with said plurality of spark-gap means and each of said current-responsive means being urged into abutting relation with one of said first electrical contact means; and

a plurality of spring means, each of said spring means abutting one of said current-responsive means and one of said electrical contact means to (l) establish conducting paths for normal circuit current at normal applied circuit voltages to (2) urge said plurality of spark-gap means into direct engagement with said grounding means and to (3) urge said projectable elements into electrical connection with said grounding means when the current in the associated circuits increases beyond the predetermined level.

10. An electrical protector assembly for protecting a circuit against excessive voltage surges and excessive current increases, which comprises:

a base member;

grounding means adapted to be connected to a ground potential for grounding excessive voltage and current in the circuit to be protected;

a voltage-protective device which includes:

a first conductor element of rigid material engaging said grounding means,

a second conductor element adapted to be connected electrically to the circuit to be protected, aligned with said first element, spaced a predetermined distance therefrom and cooperating with one end thereof to form a spark gap across which excessive voltage surges may drain off to said grounding means, and

means for supporting said first and second conductor elements in aligned, spaced relationship;

floating conductive means having a portion adjacent to the end thereof being urged into engagement with the other end of said second conductor element and having means on the other end thereof adapted to establish a sliding electrical connection with a first side of the circuit to be protected;

a current-responsive protector including:

a first conductive member engaging a portion of the one end of said floating conductive means adapted to connect the first side of the circuit to be protected to one side of the current-responsive protector,

a movable conductive member secured releasably to said first conductive member and being connected electrically thereto,

heat-generating means having one end thereof connected electrically to said first conductive member and the other end thereof being adapted to be connected to the other side of the circuit to be protected, and

heat-responsive releasable means for securing said movable conductive member normally rigidly to said first conductive member and in spaced relationship with respect to said first conductor element to permit said movable means to establish an electrical connection with said grounding means when sufficient heat has been generated by the heat-generating means as a result of current flowing in said current-responsive protector;

means attached to the base, connected electrically to the opposite side of the heat-generating means and adapted for making a sliding electrical connection to the other side of the circuit to be protected;

means for limiting relative movement of the grounding means with respect to the base, and the means for making first and second sliding electrical connections with respect to the base when connecting the protector assembly with the circuit to be protected; and

resilient means for moving said grounding means to a limit of movement of said grounding means with respect to said base for urging said first conductive member of said current-responsive protector into engagement with said floating means for, in turn, urging said voltage-responsive protector into engagement with said grounding means and also for moving the movable means of said currentresponsive protector into engagement with the first conductor element of said voltage-protective device to ground the circuit to be protected when the heat-responsive releasable means is released by an excessive amount of heat being produced by the heat-generating means.

11 12 I l 1. The assembly of claim wherein the resilient means is secured in said sleeve by said solder joint. made of conductive material and connects said heat-generat- 13 Th bl f l i 10 h i id means for li itlg ifg gsggfng g g gz zi i; i gf ts' tin ing relative movement of the grounding means with respect to e m e -g era g means is a coil of small wire, said heat-responsive releasable 5 gzz if s 2231 3 2 3: glizizsgi ggs attached to the means is a solder joint, said first conductive member is a sleeve and said movable conductive member is a pin coaxially 

1. An electrical protector assembly for protecting a circuit against excessive voltage surges and excessive current increases, comprising: retaining means for supporting the assembly; grounding means seated in said retaining means, said grounding means grounding excessive voltage surges and excessive current increases which appear in said circuit; at least one spark-gap means urged directly into abutting relation with said grounding means for conducting excessive voltage surges to said grounding means; at least one first electrical contact means for establishing contact between the circuit and the assembly, said first electrical contact means abutting said spark-gap means; at least one second electrical contact means secured to said retaining means and spaced from said first electrical contact means, said second electrical contact means and said first electrical contact means adapted to conduct normal circuit current with the application of normal circuit voltage; at least one current responsive means having a projectable element thereon for establishing an electric circuit with said grounding means when the current increases beyond a predetermined level, said current responsive means being aligned with said spark-gap means and urged into abutting relation with said first electrical contact means; and at least one spring means abutting said current responsive means and said second electrical contact means to (1) establish a conducting path for normal circuit current at normal applied circuit voltage, to (2) urge said spark-gap means into direct engagement with said grounding means and to (3) urge said projectable element into electrical connection with said grounding means when tHe current increases beyond a predetermined level.
 2. The assembly of claim 1 wherein said first electrical contact means is slidable relative to said retaining means against the force of said spring means.
 3. The assembly of claim 1 wherein said grounding means includes: a grounding pin for establishing direct engagement with the circuit to be protected; a strap member extending in said assembly and being made of a substantially flat strip of conducting material for conducting excessive voltage surges and excessive current increases from said spark-gap means and said current-responsive means to said pin member; and a pair of tabs projecting laterally from said strap member, one of said tabs being abutted by said spark-gap means and being aligned with and spaced from said projectable element of said current-responsive means and the other of said tabs supporting said grounding pin thereon.
 4. The assembly of claim 1 wherein said first electrical contact means includes: a contact pin for establishing direct engagement with the circuit to be protected; a strap member extending in said assembly for establishing a conducting path with said contact pin; and a pair of tabs projecting laterally from said strap member, one of said tabs having a closed oblong recess therein for retaining said projecting element of said current responsive means and the other of said tabs having said contact pin secured thereto with a portion of said contact pin projecting through said other of said tabs, said portion temporarily engaging and retaining said spring means when said spring means is assembled with said current-responsive means between said tabs to facilitate the subsequent assembly of the first electrical contact means and the spring means with said retaining means.
 5. The assembly of claim 1 wherein the retaining means comprises: a housing having at least one open end; a base means securable to said open end, said base means having said second contact means rigidly attached thereto; rib means extending longitudinally in said housing and projecting partially across the width of said housing, said rib means having support means thereon for supporting said grounding means in an intermediate position; slot means disposed directly opposite said rib means for retaining said grounding means in a final position, said slot means electrically isolating said grounding means from a portion of said spark-gap means, from said current responsive means and from said spring means; first and second additional slot means disposed adjacent to said rib means on either side thereof for retaining said first electrical contact means and for camming said spring means during the assembly of said electrical protector assembly; and means on said housing for securing said base on said housing after said base is slid into position on said housing.
 6. The assembly of claim 5 further comprising: said housing formed with at least one closed end; and a shoulder projecting from said closed end of said housing adjacent to said grounding means when said grounding means is seated in said retaining means, said shoulder defining a recess encompassing a portion of said grounding means and having a height greater than the thickness of said portion, said recess also encompassing a portion of said spark-gap means when said spark-gap means is correctly oriented and not encompassing a portion of said spark-gap means when said spark gap is incorrectly oriented, wherein said spark-gap means projects further from the closed end of the housing and causes said first electrical contact means to project excessively beyond said open end of said housing when said spark-gap means is incorrectly oriented.
 7. A method of assembling the electrical protector of claim 1 comprising the steps of: positioning said grounding means in said retaining means to support said grounding means in said retaining means in an intermediate position; positioning Said spark-gap means in said retaining means to locate said spark-gap means on said grounding means; moving said grounding means with said spark-gap means located thereon to a final position within said retaining means; moving said first electrical contact means with said current-responsive means and said spring means secured thereto to position said first electrical contact means in abutting relation with said spark-gap means; electrically connecting sad second electrical contact means with said spring mean; and camming said spring means out of direct abutment with said first electrical contact means simultaneously with electrically connecting said second electrical contact means with said spring means.
 8. The method of claim 7 wherein said grounding means is tilted relative to said retaining means when in said intermediate position and is longitudinally aligned with said retaining mans when being moved to said final position and when in said final position.
 9. An electrical protector assembly for protecting a plurality of normally separate electrical circuits from excessive voltage surges and excessive current increases in the circuits comprising: retaining means for supporting the assembly; grounding means seated in said retaining means for grounding excessive voltage surges and excessive current increases which may appear in any of said circuits; a plurality of juxtaposed spark-gap means urged directly into abutting relation with said grounding means for conducting excessive voltage surges in any of said circuits to said grounding means; a plurality of juxtaposed first electrical contact means for establishing contact between the circuits and the assembly, each of said first electrical contact means abutting one of said spark-gap means; a plurality of juxtaposed second electrical contact means secured to said retaining means and spaced from said plurality of said first electrical contact means, said plurality of said second electrical contact means and said plurality of said first electrical contact means adapted to conduct normal circuit current with the application of normal circuit voltage in said plurality of circuits; a plurality of juxtaposed current responsive means each having projectable elements thereon for establishing and electrical circuit with said grounding means when the current in an associated circuit increases beyond a predetermined level, said plurality of current-responsive means being aligned with said plurality of spark-gap means and each of said current-responsive means being urged into abutting relation with one of said first electrical contact means; and a plurality of spring means, each of said spring means abutting one of said current-responsive means and one of said electrical contact means to (1) establish conducting paths for normal circuit current at normal applied circuit voltages to (2) urge said plurality of spark-gap means into direct engagement with said grounding means and to (3) urge said projectable elements into electrical connection with said grounding means when the current in the associated circuits increases beyond the predetermined level.
 10. An electrical protector assembly for protecting a circuit against excessive voltage surges and excessive current increases, which comprises: a base member; grounding means adapted to be connected to a ground potential for grounding excessive voltage and current in the circuit to be protected; a voltage-protective device which includes: a first conductor element of rigid material engaging said grounding means, a second conductor element adapted to be connected electrically to the circuit to be protected, aligned with said first element, spaced a predetermined distance therefrom and cooperating with one end thereof to form a spark gap across which excessive voltage surges may drain off to said grounding means, and means for supporting said first and second conductor elements in aLigned, spaced relationship; floating conductive means having a portion adjacent to the end thereof being urged into engagement with the other end of said second conductor element and having means on the other end thereof adapted to establish a sliding electrical connection with a first side of the circuit to be protected; a current-responsive protector including: a first conductive member engaging a portion of the one end of said floating conductive means adapted to connect the first side of the circuit to be protected to one side of the current-responsive protector, a movable conductive member secured releasably to said first conductive member and being connected electrically thereto, heat-generating means having one end thereof connected electrically to said first conductive member and the other end thereof being adapted to be connected to the other side of the circuit to be protected, and heat-responsive releasable means for securing said movable conductive member normally rigidly to said first conductive member and in spaced relationship with respect to said first conductor element to permit said movable means to establish an electrical connection with said grounding means when sufficient heat has been generated by the heat-generating means as a result of current flowing in said current-responsive protector; means attached to the base, connected electrically to the opposite side of the heat-generating means and adapted for making a sliding electrical connection to the other side of the circuit to be protected; means for limiting relative movement of the grounding means with respect to the base, and the means for making first and second sliding electrical connections with respect to the base when connecting the protector assembly with the circuit to be protected; and resilient means for moving said grounding means to a limit of movement of said grounding means with respect to said base for urging said first conductive member of said current-responsive protector into engagement with said floating means for, in turn, urging said voltage-responsive protector into engagement with said grounding means and also for moving the movable means of said current-responsive protector into engagement with the first conductor element of said voltage-protective device to ground the circuit to be protected when the heat-responsive releasable means is released by an excessive amount of heat being produced by the heat-generating means.
 11. The assembly of claim 10 wherein the resilient means is made of conductive material and connects said heat-generating means to the other side of the circuit to be protected.
 12. The assembly of claim 10 wherein the heat-generating means is a coil of small wire, said heat-responsive releasable means is a solder joint, said first conductive member is a sleeve and said movable conductive member is a pin coaxially secured in said sleeve by said solder joint.
 13. The assembly of claim 10 wherein said means for limiting relative movement of the grounding means with respect to the base is a housing of insulating material attached to the base with a detent-in-slot fastening means. 